$$ integers (n, nmax, qo) =
    (n > nmax ?
        (-1) >> qo
    :
        n >> qo;
        become integers(n+1, nmax, qo)
    )

# Version alternative :
$$ integers (n, nmax, qo) =
    ]->[ (
        (n > nmax ? ->[]);
        n >> qo;
        n = n + 1
    );
    -1 >> qo

$$ filter (n, qi, qo) =
    val << qi;
    (val != -1 ?
        (val % n != 0 ?
            val >> qo
        );
        become filter(n, qi, qo)
    :
        -1 >> qo
    )

# Version alternative :
$$ filter (n, qi, qo) =
    ]->[ (
        val << qi;
        (val == -1 ? ->[]);
        (val % n != 0 ? val >> qo)
    );
    -1 >> qo

$$ primes (qi) =
    val << qi; 
    (val != -1 ?
        val >> stdout;
        c = <>;
        | become filter(val, qi, c.out) |;
        become primes(c.in)
    )

# Version alternative :
$$ primes (qi) =
    ]->[ (
        val << qi;
        (val == -1 ? ->[]);
        val >> stdout;
        c = <>;
        | filter(val, qi, c.out) |;
        qi = c.in
    )

$$ main () =
    c = <>;
    | integers (2, 5000, c.out) |;
    primes (c.in)